The present invention relates to an arrangement for runtime compensation of a runtime difference arising through emulation of a high frequency signal.
High frequency signals, transmitted by any transmission systems of a linear or non-linear nature, such as amplifier chains for example, can be emulated by signal processing devices. One example of a transmission system is set out in the patent application filed by the applicant with the same application date, relating to a sigma-delta modulator for digitizing analog high frequency signals. Ideally the signal emulation of the output signal of the transmission system proceeds without a time delay in relation to the original signal, so that the precisely emulated signal components of the emulated signal extinguish the original signal completely in a difference signal.
Practical instances of signal emulation however generally result in a runtime difference between the emulated signal and the original signal. As can be clarified below, the time delay of the emulated signal results in extinction of the signal components in a certain frequency range only. Here x(t) designates the original output signal of the transmission system and {circumflex over (x)}(t) the emulated signal; τ stands for the runtime difference of the emulated signal.
The following equation appliesx(t)−{circumflex over (x)}(t)≈x(t)−x(t−τ)X(jω)−e−jωτX(jω)=X(jω)·(1−e−jωτ)
In order to achieve broadband signal extinction, runtime elements are commonly used, which delay the signal x(t) by the period of the runtime difference τ of signal emulation {circumflex over (x)}(t).x(t−τ)−{circumflex over (x)}(t)≈x(t−τ)−x(t−τ)=0
The highly linear runtime elements used for this are technically expensive due to the high level of spectral purity of the signal x(t) and give rise to high manufacturing costs.